MassDEP Eelgrass Overview Map

Seagrass beds are critical wetlands components of shallow marine ecosystems along the Massachusetts coastline. Seagrass beds provide food and cover for a great variety of commercially and recreationally important fauna and their prey. The leaf canopy of the seagrass bed calms the water, filters suspended matter and together with extensive roots and rhizomes, stabilizes sediment. Seagrasses are often referred to as " Submerged Aquatic Vegetation" or SAV. This distinguishes them from algae, which are not classified as plants by biologists (rather they are often placed in the kingdom protista), and distinguishes them from the "emergent" saltwater plants found in salt marshes.

In addition to the term SAV, some coastal managers use the term SRV or submerged rooted vegetation. This term probably arose to avoid confusion because non-scientists considered both seagrasses and algae as "plants" or "vegetation," and did not realize the term SAV excluded algae. Eelgrass, Zostera marina, is the most common seagrass present on the Massachusetts coastline. The other species found in embayments of the Massachusetts coast is Ruppia maritima, (Widgeon grass), which is present in areas of less salinity along Cape Cod and Buzzards Bay.

The Massachusetts Department of Environmental Protection (MassDEP) began a program to map the state's SAV resources in the early 1990s and since 1995 the MassDEP Eelgrass Mapping Project has produced multiple surveys of SAV along the Massachusetts coastline.

MassDEP Eelgrass Underwater View
Example of underwater video recorded by MassDEP Eelgrass Mapping Project

Throughout the implementation of this program MassDEP has continued to adopt and utilize "state of the art" methods to ensure the scientific credibility and practical application of the SAV mapping and monitoring data collected. The MassDEP Eelgrass Mapping Project ranks among the longest sustained seagrass monitoring programs (utilizing the same methods) in the world. The program uses remote sensing to acquire data on SAV extents to monitor the status and trends of the resource state wide. This general approach is comparable to other large scale seagrass monitoring programs in the Chesapeake Bay, Virginia and the Indian River Lagoon in Florida.

Unlike several other monitoring and research programs that depend on "in water"sampling for data acquisition, MassDEP relies almost exclusively on remote sensing of aerial imagery as the principle source of information.

The remote sensing data is supplemented by "boat based" underwater video data acquisition to verify benthic habitat signatures and conduct accuracy assessments. These accuracy assessments are a hallmark of the MassDEP Eelgrass Mapping Project and ensure the scientific credibility and utility of the data.

MassDEP SAV Mapping Layers

        View these layers online to see growth or decline in many areas.

The MassDEP Eelgrass Mapping Project has produced multiple mapping layers of SAV distribution along the Massachusetts coastline. Click on the Project Year below for data documentation and download of individual MassDEP SAV layers.
Phase  Project Year(s)  Project Area
11995Entire MA Coast
22001Entire MA Coast except Elizabeth Islands (Gosnold) and Mount Hope Bay
32006/07Selected embayments, coast-wide including Elizabeth Islands
42010*Nantucket Sound side of Cape Cod, Woods Hole to Chatham, including Pleasant Bay and Selected embayments of Buzzards Bay and Martha’s Vineyard
52012*Massachusetts Bay coastline, Ipswich Bay to Provincetown
62013*Buzzards Bay, Elizabeth Islands, Martha’s Vineyard and Nantucket

* NOTE: Together the 2010, 2012, and 2013 layers cover the entire Massachusetts coastline.

For additional information on the MassDEP Eelgrass Mapping Project, visit: http://www.mass.gov/eea/agencies/massdep/water/watersheds/eelgrass-mapping-project.html.

Last Updated 7/12/2017